Portion of a display screen with a graphical user interface



FIG. 1 is a front view of a portion of a display screen with a graphical user interface showing a first embodiment of the new design; and,

FIG. 2 is a front view of a portion of a display screen with a graphical user interface showing a second embodiment of the new design.

The broken line positioned around the portion of a display screen with graphical user interface illustrates portions of the display screen with graphical user interface that form no part of the claimed design. 

CLAIM We claim the ornamental design for a portion of a display screen with a graphical user interface, as shown and described. 